Light drag in a ring laser: An improved determination of the drag coefficient

Abstract

The light drag in a rotating fused-silica disk inserted in a He-Ne ring laser was measured at $\ensuremath{\lambda}=633$ nm and found to be ${\ensuremath{\alpha}}_{e}=0.5424$ with an rms error ($1\ensuremath{\sigma}$) of \ifmmode\pm\else\textpm\fi{}2 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$, including the known error sources. This constitutes a tenfold improvement in accuracy over a previous result. While the given error margin does not include the value given by the Lorentz drag in a linear arrangement, ${\ensuremath{\alpha}}_{\mathrm{LO}}=0.54182$, the measured difference of $2\ensuremath{\sigma}$ is deemed too small to claim a discrepancy.